Free coffee is Barnes & Noble's latest means of inducing customers to use its BN e-reader software in various devices, including the retailer's own Nook, while inside its stores.

During the limited promotion period, customers who show a Barnes & Noble cafe server an open e-book on any device running the BN software can get one free tall cup of coffee. The eligible devices include the Nook along with iPads, iPhones, iPod touches, BlackBerries or HTC HD2 devices and portable Mac or Windows computers.

Barnes & Noble has long been interested in pushing the Nook as well as a range of devices as a way to support e-book sales. Also, the bookseller has promoted the pairing of e-book reading on its Nook device with in-store experiences.

The Nook software version 1.3, made available in April, offers Nook users the ability to read selected books inside a Barnes & Noble store for an hour a day at no cost.

A related promotion, called "More in Store" offers free content that can be downloaded to a Nook while in a store. Version 1.3 supports a beta version of a basic Web browser as well.

Some of the More in Store content for June include items such as the director's notes that commonly accompany a DVD of a feature film. For example, an essay exclusive to Barnes & Noble customers by horror writer Dean Koontz is described as "about the monsters that in inspired him to write about the greatest monster of all."

Barnes & Noble officials were not available to discuss the results of the in-store reading program.

Some analysts believe that for e-ink black and white e-readers like the Nook and Kindle to be successful long-term, the prices will have to fall or the devices will have to be upgraded to include color screens like the iPad.

London-based Informa Telecoms & Media recently predicted that sales of e-readers will grow to 14 million in 2013 but then fall off because of pressure from e-book content on a range of devices.

Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld . Follow Matt on Twitter at @matthamblen , or subscribe to Matt's RSS feed . His e-mail address is mhamblen@computerworld.com .